Remotely controlled radioreceiver



P 26, 1933- c. E. JOHNSON I 1,927,983

REMOTELY CONTROLLED RADIORECEIVER Filed Dec. 11, 1926 2 Sheets-Sheet 1 75 J I'l CPI/FL [Jaw/50w 93 I ATTOJPNfiY p 1933- c. E. JOHNSON REMOTELY CONTROLLED RADIORECEIVER Filed Dec. 11, 1926 2 Sheets-Sheet 2 ATTORNEY.

Patented Sept. 26, 1933 REMOTELY CONTRQLLED RADIORECEIVER Carl E. Johnson, Los Angeles, Calif.

Application December 11, 1926 Serial No. 154,147

9 Claims.

This invention relates to radio receiving sets and particularly to a remote control radio receiving set which is especially valuable in large residences, hospitals, or other institutions where it is advantageous to have complete control of the operation of a radio set from a point at some distance from the set itself.

It is common practice to install a central radio set in such buildings and run wires to remote loud speaker locations so that radio programs may be enjoyed in various parts of the building.

By this method it is impossible to control the radio set itself from the remote loud speaker station.

It is an object of my invention to provide a radio set which canbe completely controlled from a remote station.

A further object is to provide a remotely controlled radio set in which the tuning is accomplished by operating an electric motor.

It is a, further object of my invention to provide a remotely controlled radio set in which the radio broadcasting station to which the set is 'tuned is indicated at a remote control station.

' A still further object is to provide a radio set installation in which programs may be enjoyed simultaneously in different locations of a'building from a central station. v

Further objects and advantages of my invention will be made evident in the following description.

Referring to the drawings in which I illustrate a preferred form of my invention,

Fig. 1 is a schematic Wiring diagram.

Fig. 2 is a front view offthecontroller.

Fig; 3 is a side view of the controller.

Fig. 4 is a fragmentary view showing the means of mounting the'motor in relation to the tuning element.

Fig. 5 is a partially sectioned view taken substantially on the line 5-5 of Fig. 4. v Fig. 6 is a detailed, front view showing the ad just-able contactors.

Fig. 7 is a detailed side view of one of the contactors." t f Referring in detail to the drawings. Fig. 1 shows a radio receiving set 10 adaptedto'be controlled by a portable controller 11 from one of a number of remote control stations. In Fig. 1 two of these remoteicontrol stations 12 and 13 are shown diagrammatically, each, consisting of a wall receptacle 14 into which a multi-circuit plug 15 maybe plugged. This plug is connected to the portable co'ntrollerl-l by a cable' lfi'. I As best shown in Figs. 1, 4 and 5; the radio set ra dio set 10 by hand.

denser 21 extends through an opening 26 of the panel 23 and has a tuning dial 27 mounted rigidly thereon for hand operation of the tuning device. A metal spiral gear plate 28 is also mounted on the shaft 25 and. held rigidly 55 place by a set screw 29. f

Adapted to mesh with the gear plate 28 is a worm gear 30 mounted on a shaft 31 of a motor 32. The motor 32 is preferably of the slow speed, direct current type having an armature'33 and 79 a field winding 34, as indicated diagrammatically in Fig. 1. A pin 37 is mounted in the panel23 and rotatably supports the motor 32 as shown in Fig. 4. Extending downward from the left end of the motor 32 is a follower. 38 which is adapted ,75 to be engaged by a cam 39 pivoted to the panel 23 at 40. An arm 41 .of the cam 39 extends through an arcuate opening 42 of the panel 23. The cam39 is so designed'that when the ariii 41 rests in the lower part of the arcuate opening no 42 the follower 3.8 engages .thecam 39 in such a way as to hold the motor 32in the position shown in full lines, thus meshing the wormfgear 30 with the gear plate 28. When the arm 41 rests in the upper part of the opening 42 in the posi- 35 tion shown by dotted lines 43, the cam 39 allows the pin 37, and consequently disengagingthe .worm gear 30 and the gear plate 28. This 'disengaged position of the' worm 30 is indicated by dotted lines 44, and when in this positioirallows "the -tuning device to be freely rotated by of the dial 27 so that it is possible to operatetlie The motor 32 adapted to be operated by a ,motor control switch mounted in the portable controller-.11. The mechanism of the "shown diagrammaticallyas comprising an insulating support 54 which is attached to a shaft 1 '52 which extends through a front, p1atej53 of ,th'e'portable controller ,11, and which supports radiarm'etallic .arms 55 and'56. The arm.'55 acts'as a "contact a'rm forforward variable resistance 58'when the shaft 52' is rotated'in a1 clockwise, direction, this being accomplished by pperatingf'a 14110551; which is'secured t6 the shaft 52.;The rightend of the forward resistance 58 is jconnec'te' d'by a" wire 59 to the left side or the, armaturefqof the motor; 32. .When the ,1

knob 51 clockwise and counter-clockwise.

knob 51-is rotated in a counter-clockwise direction the arm 55 acts as a contact arm for reverse variable resistance 60, the left end of which is attached to the right side of the armature 33 by a wire 61. Compression springs 62 engage the arm 55 and are adjusted to always return the switch to its off position shown in Fig. 1 when the knob-51 is released.

Simultaneously with the arm 55 contacting the forward resistance 58 when the knob 51 is rotated in a clockwise direction, the arm 56 engages anauxiliary contact 63 and a field contact 64. The auxiliary contact 63 is connected to the left end of reverse resistance 60 by a wire 63'. The field contact 64 is attached to one terminal of the motor field 34 by a wire '66. When the knob 51 is rotated counter-clockwise, the arm 56 engages an auxiliary contact 68 and a field contact 69. The auxiliary contact 68 is connected to the right end of the forward resistance 58 by a wire 68 The field contact 69 is connected to the field contact 64 by a wire 70. The arm 55 is connected to a wire 72 through a flexible lead. The wire 72-is joined by wires73 and '74 to the positive side of a storage battery 75. The arm 56, on the other hand, is connected 'to the negative side of the battery 75 through a flexible lead, wires 76, 77 and 78, contact elements 79 'and80' of a magnetic switch 82 and wire 83. A wire 83* connects the upper terminal of the field 34 to the wire 73.

The motor controlswitch 50 offers a means of starting, stopping, reversing, and varying the speed of the motor32 of the radio set 10, thus controlling the movement and position of the tuning device. When turned clockwise the switch 50 sends current through the armature 33 in an opposite direction than when turned counter-clockwise, but does not vary the direction of the current flowing through the field 34 of the motor 32. This causes the motor 32 to rotate in opposite directions'with the rotating of the The angular displacement of the knob 51 determines the position of the arm 55on the forward or reverse resistances 58 and 60, which in turn varies the amount of resistance in the armature, circuit of the motor 32. Thus when the arm 55 first makes contact with one of the resistances a 'maximum resistance is placed in series with the armature 33, thus causing the motor 32 to rotate very slowly. Further movement of the knob 51 cuts out resistance, thus increasing the speed of the motor 32, the maximum speed being attained when the resistance is out completely out of the circuit by the arm 55 making direct contact with either the wire 59 or the wire 61, depending on whether the motor 32 is running forward or backward.

The magnetic switch 82 is operated by the energizing of one of two oppositely disposed solenoids 84 and 85. This is accomplished remotely by means of an operating switch 86 mounted in the portable controller 11 and actuated by a knob 87 pivoted on the face thereof. The knob 87 rotatably supports a contact arm 88 which is connected to the negative side of the battery 75 by a wire 89. When the arm 88 is rotated clockwise, it engages a contact point 90 which is connected to the upper terminal of the solenoid 84 of the magnetic switch 82 by a wire 91. Rotating the arm 88 in a counter-clockwise direction allows it to engage a contact point 92 which is connected to the lower terminal of the solenoid 85 by a wire 93. The lower terminaljof the solenoid 84 and the upper terminal of the solenoid 85 are joined by a wire 95, to which a wire 96 is attached which leads to the positive side of the battery 75. Rotating the knob 87 clockwise therefore energizes the solenoid 84, while counter-clockwise rotation energizes the solenoid 85. The arm 88 is always brought to the off position, shown in Fig. 1 by means of a tension spring 97 attached thereto.

Operating in the magnetic fields of the solenoids 84 and is an armature 100 pivoted about a point 101 and so placed that the right end of the armature 100 is-acted upon by the energizing of either of the solenoids 84 or 85. The left end of the armature 100 is adapted to engage the contact element 80 of a compound jack 103 when the armature 100 is in the dotted line or on position indicated at 104. The jack 103 comprises contact elements 79 and 80, mentioned previously, and contact elements 106 and 107, all mounted in an insulation block 108. When the solenoid 84 is energized the armature 100 is drawn into its dotted line position 104'. This causes the left end of the armature 100 to engage the contact element 80, moving it to theleft into its dotted line position, at which time it is in contact with the contact element 79. An insulating strip 109 transmits this motion from the contact element 80 to the contact element 106 and causes the latter to engage the contact element 107.

It should be understood that any number of contact elements may be placed in the jack 103, depending on the number of circuits to be controlled by the magnetic switch 82, in turning the radio set 10 on and off, which in turn will depend on the type of radio set being used. I have shown a pair of power amplifier input terminals 110 and 111 mounted on the panel 23 of the raio set 10. A wire 112 connects the terminal 111 and the contact element 107. The terminal 110 and the contact element 106 are shown connected to a source of alternating current power by wires 113 and 114 respectively. Thus, when the armature 100 is in the dotted line position 104, the contact elements 106 and 107 will be in engagement and will supply the alternating voltage required for this type of power amplifier to the power amplifier input terminals 110 and 111.

Filament current is supplied to the radio set 10 through terminals and 121 which are connected respectively to the wires 73 and 77. A wire 122 or B current is furnished through conventional B batteries, not shown.- I

Mounted on the supports 24 of the variable condenser 21 is a contact plate made of insulating material in which a compound, semi-circular groove 131 is cut, this groove 131 supporting a number of adjustable contactors 134 as best shown in Figs. 5, 6 and 7. The contactors 134 have body members 135 with legs 136 and 137 extending in parallel directions from diagonally opposite corners of the body members 135. The leg 136 is adapted to fit in the compound groove 131 while the leg 137 lies fiat against a face 139 of the conplate 130, and once inserted can be moved in the semi-circular path offered by the groove. A brush 141 is mounted on the gear plate 28 in such a position as to successively contact the legs 137 of the .eontscto s 134- wheni'thersearplate 881: rotated- In Big. 1.v six contactors 134 are shown mounted in the contact plate and are numbered'i'rom -144 to 149 inclusive. Connectedto the contactors -5 144 to 149 inclusive, hrough flexible leads. are

wires 150 to inclusive which are connected vto one terminal otrtheir respective-signallights to inclusive which are mounted .;on;the. .tace

oi the portable controller-d1 in a circular .er-

; lo rangement. Thus,..the contactor 144 isjconnected .to the signal light 160 through the wire-:15Qbthe eontactor 145, to the signal li ht 161 throu h. the

wire 151, etc.- Theremainingterminalsofpeach or the signal lamps 160-t0 .165 inclusive are 15 connected together, by means or a wire 167 which is joined to the wire-77.; The signal. lights-1'00 to 165 inclusive arefor the purpose-o! indicating the position or the variable condenser 21 to the operator stationed a-t the portable controller 11.

-2 They are so wiredthatany once! the signal lights will be lit when its respective contactoris engaged by the brush 141,. provided that the magnetic switch 82 is in its on"- position as shown by the dotted lines 104..,.'I'hus when the 2 brush 141 engages the contactor 144, the signal light 160 will light. The :contactors 144 to 149 inclusive may conveniently be adjusted in the groove 131 so, that they light, their respective signal lights when diflerent broad-casting sta- 30 tions are tuned in. Thus in Fig. z'these signal lights are shown accompanied bythe call letters of their respective stations. The signal light .buming always indicates-to the operator at the remote control station the. station tuned in and 2. .5 also the relative position of theyariable, condenser plates 22. 1

A pilot lamp 170 is mounted to the left of the knob 87101 the. portable controller 11 for the purpose or indicating the position .of the-magnetic switch 82; The'wires 77 and 73 terminate at the, terminals, of the pilot -lamp: 170 and conducticurrent from {the battery-75 when the magnetic switch 82 is in the on position. The multi-circuit plug 15, toi-whichthe portabl -controller ,11 is 'connectediby the cable 18, is

-,adapted to fit any+of the wall receptacles 14 of the remote controlstations 12 and,-13.- The multiclrcuit plug 15 is composed of a plurality of pins which are adapted to, snugly engage iemale -members 176 of theiwallireceptaclesl l when the .plug 15 is. inserted therein.- Eachot thewires in the cable 16 is connected to onset the pins 175 and each female member-176$ connected to a wire leading to the locational theradlo set 10.

Mounted in, thecenterof-the multi-circuit plug 15 is a conventional loud speaker plug 17'! consisting of -a shank 178 and a-tipl'lQ which;are

adapted to engage a'shank contact 180 and a tip I.contact'181 of a jack 18.3 mounted in the center of each 01 thex'wallreceptacles-14. The tip-J79 and shanki178 are shown connected byv leads 1 and 186' to a loud speaker iack'190;mou nted on =the' face 53.01 .the portable controller 11; A loud speaker 191 is connected to the loud speaker jack (J .190 through a plug (not shown) which is identical in construction and sizeflwith the, loud speaker -.=plug 17? mounted in they center of the multi,-,cir 'cuit plug 15. Thus aloud speakenwith its conzventional plug may be plugged into the-jack 190 mounted on the portable controller 11, orit may he plugged directly into any of the wall receptacles 14. where it will contact the-tip contact 181 and the'shankcontact 180: iThese-tip and shank con- 75 tacts 181 and 180v are shown connected to output terminalstl93 and 194. 01. the radios-M419 11110 18 1 ;wlresand 19.6 r spectively... Throughout Fig. 1 :,the loudg' speakuerv leads are BhOWn in heavy-lines for the sake or clearnessin checking out the cir- ,cuits. A variable resist nce 198 is shown mount- ,ed, the base oli he. loudspeaker 191and con-. nected across the terminals thereof tor the purposeol regulating thevolume of sound produced. =1 Beca se allgthe remote control stationstarc wiredin parallel in all respects, it should be clear uthat whennthe radio set .10 is; being controlled ti-om one remote contro station, 1. e., the station 13 for instance, the same; program maybe enjoyed at other remote control-stations; such as 12, .by insertih zthev plugof a loud speaker in, the

jack 5181 oI-the-wallreceptacle 14'situated at the i remote control station 12. i This connects the loud speakers at the-stations 12 and 13 in parallel and the volume maybe diminished by adjusting the ;,variable resistance 198. and thus shunting a portion of, the loud speaker energizing currentthrough this resistance. .In thus operating a motor in the vicinity-of a radio set a click is sometimes experienced when the motor controlling switch 50 is first rotated, due to the motor field acting on the wires inside .the radio set and inducing a slight potential ctherein. I have found that all trouble from this source canbe eliminated by shielding the motor 32 with a metal shield and shunting boththe xarmature terminals and the field terminals with 105 i a fixed resistance of about 200 ohms. In Fig. 1a resistance 200 is shown shunted across the termiof the armature, 33 and a resistance 201 is shown shunted across the terminals of the field'*- 3,4.-

The operation of my invention is substantially qas follows.

The portable controller 11 is carried to any desired remote control station and is placed at any convenient location in the room within reach 115, V

. of the wall receptacle 14 through the cable 16. The multi-circuit plug 15 is inserted in the wall receptacle-:14, thus connecting the wires inthe cable-16 to;.corresponding wires leading to the .radlo set ill l. The loudspeaker 191 is plugged 120 into the jack 190.01j-the portable controller 11. The operatingswitch' 86 is momentarily moved ina-clockwise direction,- thus making contact between the arm 88, and the contact point 90. with the switch in this position, current flows @125 from the positive side of the battery 75, through the wires 86 and 95, through the solenoid.84, and the wire91 to thecontact point 90, whence it is conducted through the -arm 88 and the wire 89 tome-negative side of the battery 75. .currentrenergizges the-solenoid 84, causing it to ,attract the armature 100, moving it into the dotted line position shown at 104, where it remains untilthesolenoid 85 is energized.- when the knob 87 of the operating switch 86 is re- 1eased,;the spring 97- returns it to its mid position, thl1 opening the circuit through the solen d-8 .7 ,-When thei armature 100 is. in the dotted line I position shown I at, 1.04,, the contact elements 79 and More in en agement as well as the contact elements 106 and 107. completes a circuit from the positive. side of the battery 75- through ..the -wire s 74 and -73--to the filament terminal 1 120, whencethe-current energizes the filaments of theyacuum tubes in the radio set 10, returnzingto the; negative side of the battery. 75 by oi. the terminal 121, the wit-e77, the wire ,78, gthe contactelements 79 ,and; 80.- andq he w re-: 3, noth r c r t-hammered rom th source of alternating current power through the wire 114, the contact elements 106-and 107, and the wire 112 to the power amplifier input terminal -111, whence it returns to the source of alternating current power through the terminal 110 and the wire 113.

Yet a further circuit is completed from the positive side of the battery 75 through the wire 74 and the wire '73 to the pilot lamp 170, whence it returns to the negative side of the battery 75 through the wires 77 and 78, the contact elements 79 and 80, and the wire 83. This lights the pilot lamp 170. Last of all, in the event that the brush 141 is contacting one of the contactors 134, for example, the contactor 144, current will flow from the positive side of the battery 75, through the wires 74, 73, and 122, through the shaft 25, the gear plate 28, the brush 141, the contactor 144, and the wire 150, to the signal light 160, whence it returns through the wires 167, 77, and 78, the contact elements 79 and 80, and the wire 83 which terminates at the negative terminal of the battery 75. This lights the signal light 160. Similar circuits can be traced if thebrush 141 were touching any other contactor 134, in which case the corresponding signal light on the portable controller 11 would be lit.

In case the operator desires to tune the radio set to a different wave length he moves the motor controlling knob 51 either clockwise or counter-clockwise, depending on whether the wave length is to be raised or lowered. Turning the knob 51 clockwise completes a circuit from the positive terminal of the battery 75 through the wires 74, 73, and 72 to the arm 55 of the motor controlling switch 50. The arm 55 is at this time contacting the forward resistance 58 through which the current passes on its way to the armature 33 by way of the wire 59. Passing through the armature 33 the current is conducted through the wires 61 and 63 to theauxiliary contact 63, whence it goes through the arm 56, wires 76, 77, 78, the contact elements 79 and 80, and the wire 83 to the negative terminal of the battery 75. Simultaneously a circuit is completed through the field 34 asv follows. From the positive terminal of the battery current flows through the wires 74, 73, 83 through the field 34 of the motor 32, to the field contact 64 by means of the wire 66, whence it passes through the arm 56, the wires 76, 77, '78, the contact elements 79 and 80, and the Wire 83 to the negative terminal of the battery 75. The armature and field of the motor 32 being now energized, the armature will turn,

thus turning the variable condenser 21. As explained above, the speed of the motor 32 will be governed by the amount of rotation of the knob 51.

Turning the knob 51 in a counter-clockwise direction completes a circuit from the positive side of thebattery 75, through the wires 74, 73 and 72, the arm 55, the reverse resistance 60, the wire 61, the armature 33, the wire 59, the wire 68*, the auxiliary contact 68, the arm 56, the wires 76, 77, 78, the'contact elements 79 and 80, and through the wire 83 to the negative side of the battery 75. It should be noted that the armature current has reversed in direction with the turning of the nob 51 in a counterclockwise direction. The field current, however, does not reverse, traveling from the positive terminal of the battery 75, through the wires 74, 73 and 83, through the field 34, the wire 66, the wire 70, the

turned position until the desired station is tuned" in, which will be indicated by the lighting of the proper signal lamp. The knob 51 is immediately released, or if the variable condenser 21 has been turned a trifle too far the knob 51 may be momentarily reversed, thus reversing the motor 32 and turning the variable condenser back. Thus a very delicate adjustment can be effected.

The volume of sound produced can be regulated either by shunting some of the loud-speaker current through the resistance 198 or by detuning the set; that is, by regulating the position of the variable condenser 21 so that it is a trifle to one side of the exact setting for loudest receptionof the desired station.

In turning the set off, it is only necessary to momentarily rotate the knob 87 in a counterclockwise direction and release it. This momentarily completes a circuit from the positive terminal of the battery 75, through the wires 96 and 95 to the solenoid 85, thence through the wire 93 to the contact .point 88, where the current is conducted to the arm 86, returning to the negative terminal of the battery 75, through the wire 89. This current energizes the solenoid 85, thus pulling the armature 100 from its dotted line position 104 into its full line position which in turn opens the jack 103 and its attendant circuits previously described.

It should be noted that turning the knob 51 before throwing the magnetic switch 82 by means of the knob 87' will have no effect on the motor insofar as the contact elements 79 and 80 are separated. Neither will any of the signal lamps be lighted unless the magnetic switch 82 is first closed.

In the event that it is desired to operate the radio set 10 from the set itself, all that is necessary is to move the arm 41 of the cam 39 into the position shown at 43 which disengages the worm gear 30 and the gear plate 28, thus allowing the condenser 21 to be turned by means of the dial 27. The control of the magnetic switch 82 is effected by manually moving the armature 100 into the desired position.

I claim as my invention:

1. In combination: a-radio set having a tuning device; operating means for operating said tuning device; means situated at a remote point for actuating said operating means; an operating switch adapted to turn said radio set off and on; means at said remote point for controlling said operating switch; signal lights situated at said remote point; and means controlled by said tuning device for individually energizing said signal lights to indicate the particular station to which said radio set is tuned.

2. In combination: a radio set having a tuning element; a shaft in said tuning element; a gear plate mounted on said shaft; a reversible electric motor; gearing connecting said gear plate and said electric motor; means for disengaging said gearing; a series of remote control stations wired to said radio set; a controller at one of said remote control stations; means for operating said electric motor from said controller; signal lights on said controller indicating the position of said tuning element of said radio set; a magnetic switch adapted to turn said radio set on and off; means situated on said controller for operating said magnetic switch; a pilot lamp on said controller adapted to indicate the position of said magnetic switch; and a loud speaker situated at any of said remote control stations.

3. In combination: a radio set having a tuning element; a shaft on said tuning element; a geaz plate carried by said shaft; electrically-operated means adapted to turn said shaft to adjust said tuning element; a remote control station; means at said station for controlling the operation of said electrically-operated means; a stationary plate, said plate having a groove concentric with the axis of said shaft; contactors adjustably mounted in said groove; a brush contact carried by said gear plate, said brush contact making contact with said contactors as said tuning element is adjusted; and indicating means at said remote control station for indicating which contactor said brush contact is engaging.

4. In combination: a radio set adapted to be tuned to the wave-length of a series of broadcasting stations; a remote control station; a plurality of signal lights at said remote control station for visibly indicating the broadcasting station to which said radio set is tuned, said signal lights being placed in the order of the wavelengths cf the stations they represent; and means operatively connecting said radio set to said signal lights for energizing said lights to indicate the broadcasting station to which said radio set is tuned.

5. In combination: a radio set having a tuning element; a motor in said radio set adapted to actuate said tuning element; a controller wired to said radio set; a control switch on said controller, said control switch being adapted to operate said motor; an operating switch on said controller; a magnetic switch adapted to turn said radio set on and off, said magnetic switch being operated by said operating switch; signal lights on said controller; and means interconmeeting said tuning element and said signal lights for individually illuminating said signal lights to indicate the station to which said radio set is tuned.

6. In combination: a radio set having a tuning element; a motor in said radio set adapted to actuate said tuning element; a controller wired to said radio set; a control switch on said controller, said control switch being adapted to operate said motor; an operating switch on said controller; a magnetic switch adapted to turn said radio set on and ofi, said magnetic switch being operated by said operating switch; a pilot light on said controller, said pilot light being lighted when said magnetic switch is in an on position; and signal lights on said controller, said signal lights being adapted to indicate the station to which said radio set is tuned.

7 In combination: a radio set; a receptacle at a remote control station, said receptacle being wired to said radio set; a primary loud-speaker jack in said receptacle connected to the output of said radio set; a plug adapted to removably engage said receptacle; a controller electrically connected to said plug and adapted to control some element of said radio set; a secondary loud-speaker jack on said controller electrically connected to said primary loud-speaker jack when said plug engages said receptacle; a loudspeaker; and a plug on said loud-speaker and attachable to either said primary or said secondary loud-speaker jacks.

8. In combination: a radio set having a tuning element; a shaft on said tuning element adapted, when rotated, to tune said tuning element to stations of different wave-length; a brush contact adapted to rotate with said shaft; contactors adjustably mounted concentric with the axis of said shaft and adapted to be respectively contacted by said brush contact; and signal lights electrically connected to said contactors and said brush contact whereby the station to which said radio set is tuned is indicated by the lighting of the corresponding signal light.

9. In combination: a radio set providing a tuning element adapted when moved to successively tune in stations of different wave-length; a plurality of signal lights, each of said signal light's being associated with one of said stations; a circuit for each signal light; contact means for successively energizing the circuits of said signal lights when said tuning element is tuned whereby the operator may visibly know the station to which the set is tuned; and sound-reproducing means oonnected to said radio set and within hearing of said operator whereby said tuning element may be audibly tuned exactly to the wave-length of the station corresponding to the signal light which is lighted.

CARL E. JOHNSON. 

